Wood panels, generically termed "reconstituted wood panels", include such fabricated products as plywood, flakeboard, hardboard, particleboard, waferboard, oriented strand board and the like. Such panels are manufactured in the form of large, relatively thin, sheets. Typically, such a panel might be about four feet in width and eight feet in length.
As a consequenc of the process of manufacture, such panels display a greater propensity to warpage and sagging than a natural wood product.
It is desirable, therefore, to be able to establish, relatively quickly and by using a non-destructive testing technique, values for the panel which can be used to calculate a measure of the modulus of elasticity of the panel. It is known that modulus of elasticity (MOE) determined by slow static methods correlates with the modulus of rupture (MOR) of wood based panels.
It is also known, in the prior art, to determine the modulus of elasticity of a thin elongate beam using a transverse vibration technique. This method involves simple support on knife edges across each end of the beam, inducing vibration of the beam and measuring the resonant frequency thereof. The modulus of elasticity is derivable from the equation given herebelow. ##EQU1## where E.sub.d is the dynamic modulus of elasticity;
w is the weight of the panel; PA1 L is the span distance; PA1 f is the resonant frequency (H.sub.z); PA1 b is the width; PA1 h is the thickness; and PA1 k is the constant for mode of vibration and acceleration due to gravity.
However, the acknowledged teaching in the prior art has concluded that the above-cited relationship, whilst applicable to slender beam members is not functional when dealing with enlarged "plate" or panel units. In practical terms, the difficulties of supporting a panel on knife edges across each end, due to the warpage and configuration thereof, and measuring the resonant frequency using prior art techniques, have appeared to prevent vibration being successfully applied to wood panels.